Heavy metal accumulation in and food safety of shark meat from Jeju island, Republic of Korea

Shark meat is consumed as a food source worldwide, especially in Asian countries. However, since sharks are apex predators in the ocean food chain, they are prone to bioaccumulation of heavy metals. More than 100 million sharks are caught annually for human consumption, and the safety of shark meat cannot be overemphasized. Here, we examined heavy metal concentration in the muscle tissue of 6 shark species including 3 migratory species (Carcharhinus brachyurus, Carcharhinus obscurus, and Isurus oxyrinchus) and 3 local species (Triakis scyllium, Mustelus manazo, and Cephaloscyllium umbratile) from fish markets in Jeju Island, Republic of Korea. The concentrations of 11 heavy metals (Cr, Fe, Cu, Zn, As, Se, Cd, Sn, Sb, Pb, and Hg) and MeHg were analyzed. The result showed that the average concentrations of all metals, except for that of As, were below the regulatory maximum limits of many organizations, including the Codex standard. Hg and MeHg were significantly correlated with body length, body weight, and age, and the concentration of Hg was expected to exceed the limit in C. brachyurus with a body length or weight of over 130 cm or 25 kg, respectively. Our results indicate that shark meat can expose consumers to a high level of As and that copper sharks bigger than the predicted size should be avoided for excessive Hg. Considering these findings, a detailed guideline on consumption of meat of different shark species should be suggested based on further investigation.

鲨鱼肉在全球范围内均作为食物被食用，在亚洲国家尤为普遍。由于鲨鱼是海洋食物链中的顶级捕食者，极易发生重金属的生物富集作用。每年有超过1亿条鲨鱼被捕捞以供人类食用，因此鲨鱼肉的安全性无论如何强调都不为过。本研究针对韩国济州岛各鱼市售卖的6种鲨鱼的肌肉组织，开展了重金属含量检测：其中3种为洄游性物种，分别是短鳍真鲨（Carcharhinus brachyurus）、暗体真鲨（Carcharhinus obscurus）、尖吻鲭鲨（Isurus oxyrinchus）；另外3种为本地栖息物种，分别为条纹斑竹鲨（Triakis scyllium）、星貂鲨（Mustelus manazo）、阴影绒毛鲨（Cephaloscyllium umbratile）。本研究分析了11种重金属及甲基汞（MeHg）的含量，涉及的重金属包括铬（Cr）、铁（Fe）、铜（Cu）、锌（Zn）、砷（As）、硒（Se）、镉（Cd）、锡（Sn）、锑（Sb）、铅（Pb）与汞（Hg）。结果显示，除砷外，所有重金属的平均含量均低于包括食品法典标准（Codex standard）在内的多家国际组织制定的最大残留限量。汞（Hg）及甲基汞（MeHg）的含量与鲨鱼的体长、体重及年龄均呈显著相关性；当短鳍真鲨体长超过130 cm或体重超过25 kg时，其体内汞含量预计将超出限量标准。研究结果表明，鲨鱼肉会使消费者面临较高的砷暴露风险，且体型超出上述阈值的短鳍真鲨因汞含量过高，应避免食用。综合上述研究发现，后续需开展进一步调查，据此制定针对不同鲨鱼物种肉品的详细食用指南。